Unofficial Fallout 4 Patch

You're right about the global becoming higher that 1 when she becomes a synth. I decompiled QF_COMCurieQuest_0016454E using Champollion, and it sets ComCurieIsSynth to 100 when executing quest stage 300, and ComCurieIsRobot, which defaults to 100, becomes 0. This affects quite a bit more than just the companion swap lines. Looking for references in FO4Edit, I found the following:

Lines that test COMCurieIsSynth = 1:
[INFO:00075D71] ('But of course, Monsieur Codsworth. I assure you, no harm will befall your master.' in GRUP Topic Children of [DIAL:001869A5])
[INFO:00075D72] ('But of course, Monsieur Codsworth. I assure you, no harm will befall your mistress.' in GRUP Topic Children of [DIAL:001869A5])
[INFO:00075D6C] ('Miss Curie, do take the utmost care of my master. I trust you're fully capable of handling your new body?' in GRUP Topic Children of [DIAL:001869A6])
[INFO:00075D6F] ('Miss Curie, do take the utmost care of my mistress. I trust you're fully capable of handling your new body?' in GRUP Topic Children of [DIAL:001869A6])
[INFO:001898BE] ('But Monsieur Danse, how have I offended you?' in GRUP Topic Children of [DIAL:001869A5])
[INFO:001898A3] ('Get out of my way, synth.' in GRUP Topic Children of [DIAL:001869A6])
[INFO:0016471A] ('But now... You make many decisions that make me want to pull my hair out.' in GRUP Topic Children of [DIAL:00164629])
[INFO:001647A1] ('Although, I am made of organic material now many things I hold onto from my original programming.' in GRUP Topic Children of [DIAL:00164661])
[INFO:0016995D] ('Surely you can think of some synths that do not deserve to die. Surely.' in GRUP Topic Children of [DIAL:001698AB])
[INFO:0016E9BD] ('Hmm. This smells quite... potent.' in GRUP Topic Children of [DIAL:0016E93D])
[INFO:0016E9ED] ('The Colonial Taphouse. Sounds so authentic.' in GRUP Topic Children of [DIAL:0016E945])
[INFO:0016EA05] ('Oh, I think he just insulted you.' in GRUP Topic Children of [DIAL:0016E943])
[INFO:0016EA11] ('Certainly, sweetheart. What'll you have?' in GRUP Topic Children of [DIAL:0016E941])
[INFO:0016EA1D] ('Alcohol? No, I serve nectar. Nectar of the gods. Bobrov's Best.' in GRUP Topic Children of [DIAL:0016E94D])
[INFO:0016EA29] ('Oh, a bar. I have read so much about places like this.' in GRUP Topic Children of [DIAL:0016E93F])
[INFO:0016EA35] ('What a fascinating place.' in GRUP Topic Children of [DIAL:0016E94B])
[INFO:0016EA41] ('He is joking with me? The pulling of the leg. I say, humans are so confusing.' in GRUP Topic Children of [DIAL:0016E949])
[INFO:0016EA4D] ('But, of course, madame. What do you require?' in GRUP Topic Children of [DIAL:0016E947])
[INFO:0016EA59] ('I am new to this whole drinking activity. I will have what you recommend.' in GRUP Topic Children of [DIAL:0016E944])
[INFO:0016EA7D] ('Pardon me, monsieur, I would like a drink.' in GRUP Topic Children of [DIAL:0016E942])
[INFO:0016EAA1] ('*laugh* Very funny. Tell you what, have this on the house.' in GRUP Topic Children of [DIAL:0016E940])
[INFO:0016EAC5] ('After you try Bobrov's Best, you will disagree. Mark my words.' in GRUP Topic Children of [DIAL:0016E94C])
[INFO:0016EAD1] ('I would like a Rum and Nuka-Cola. With a bunch of cherries, please.' in GRUP Topic Children of [DIAL:0016E93E])
[INFO:0016EAE9] ('The gods? You think to fool me. There is no proof of any divinity in all my records.' in GRUP Topic Children of [DIAL:0016E94A])
[INFO:0016EAF5] ('Excuse me, barkeep.' in GRUP Topic Children of [DIAL:0016E93C])
[INFO:0016EB0D] ('Monsieur. Do you serve alcohol here?' in GRUP Topic Children of [DIAL:0016E948])
[INFO:0016EB31] ('Ten caps. You are welcome here anytime. Especially if you don't bring your shabby friend.' in GRUP Topic Children of [DIAL:0016E946])
[INFO:00173C2B] (in GRUP Topic Children of [DIAL:0016DA38])
[INFO:00174B36] ('*cough* What... What was that? This gas. In my throat?' in GRUP Topic Children of [DIAL:0016D372])
[INFO:001A0B02] ('Something familiar about your lady friend. I can't quite put my finger on it.' in GRUP Topic Children of [DIAL:0019E21A])

Lines that test ComCurieIsSynth <> 1:
[INFO:00174B37] ('My sensors detect a high level of an unknown agent in the atmosphere. I recommend extreme caution.' in GRUP Topic Children of [DIAL:0016D372])

Line I noticed that tests ComCurieIsRobot = 1:
[INFO:001A0B01] ('A lady Mister Handy? You should introduce her to Old Rusty.' in GRUP Topic Children of [DIAL:0019E21A])

Lines that test COMCurieIsSynth <> 0 or > 0:
[INFO:001869AD] ('Unlike you, I did not undergo such a procedure on a whim.' in GRUP Topic Children of [DIAL:001869A5])
[INFO:001869A9] ('I like the new look, Curie. And people give me a hard time just for swapping out my face.' in GRUP Topic Children of [DIAL:001869A6])
[INFO:00188B08] ('I have survived centuries more than you, monsieur.' in GRUP Topic Children of [DIAL:001869A5])

Ugh, this also affected one of our retroactive quest fixes for Curie as well which was expecting that value to be == 1, not == 100. So that never actually got done. Issue #22777 to be exact. So that's going to need to be transferred to the retro script for 2.1.4 now.

Such a mess.